Oxygenation wand and small batches

I do a lot of 2.5 gallon batches. When I use the O2 system on a 2.5 gal batch, I should just use 1/2 the amount of O2 I'd use in a 5 gal batch, right?

Doing that just feels strange though. If I go by William's Brewing's recommendation of 25 seconds, then I'd have the O2 on for 12 seconds and that just doesn't feel like enough. But I don't want to use more than I have to because those Bernz-o-matic tanks cost a few bucks. Any thoughts?

Oxygen absorption depends on the density and temp of the wort. Higher gravity means less O2 absorption, so you'd need to run the O2 longer to get the same amount of absorption.

You're adding it to wort before pitching, so temp would be pretty constant, +/- a few degrees, batch to batch. If you're brewing 1.040-1.050-ish ales, then you'd probably only need 10 seconds of O2.

If you're making a lager or a high gravity beer, you'd need a lot more O2, and in those cases, I'd still probably go with 25-30 secs.

Sounds great - thanks!